Reference to any prior art in this specification does not constitute an admission that such prior art forms part of the common general knowledge.
Various techniques have been used to monitor wounds, ulcers, sores, lesions, tumors etc. (herein referred to collectively as “wounds”) both within hospitals and outside hospitals (e.g. in domiciliary based care, primary care facilities etc.). Manual techniques are typically labor-intensive and require examination and contact by skilled personnel. Such measurements may be inaccurate and there may be significant variation between measurements made by different personnel. Further, traditional approaches may not preserve any visual record for review by an expert or for subsequent comparison.
A number of techniques for the automated monitoring of wounds have been proposed; see for example U.S. Pat. No. 6,101,408, U.S. Pat. No. 6,873,340, U.S. Pat. No. 4,535,782 and U.S. Pat. No. 5,967,979. A common approach is to place a reference object next to the wound and determine the size of the wound utilizing the scale of the reference object. It is often undesirable to place a reference object near to a wound and this requires an additional cumbersome step for a user and risks contamination of the wound. Further, when the target is not in the plane of the wound, or if the wound is not planar, there will be errors in any area calculation.
Other systems, such as that described in US2004/0136579, require the camera always to be positioned with a guide against the patient's skin. While this consistently positions the camera a desired distance from the surface to be photographed and therefore sets the scale of the image, it is unwieldy and requires undesirable contact with the skin, risking contamination of the wound.
Many prior systems also suffer from high cost, which limits uptake of the systems.
The Applicant's prior specification published as US2009/213213 proposed a handheld surface measuring device based on a structured light device. (The contents of that specification are hereby incorporated by reference herein.) A laser fan-beam was projected at a known angle to a camera optical axis and the resulting image data could be used to measure wound properties such as area or depth. However, the Applicant has recognized that further improvements in wound measurement are possible.
It is an object of the invention to provide an improved device for monitoring or measuring skin features, or to at least provide the public with a useful choice.